Whats a good scrub?

ok, so we are looking at the formula for our new micro exfoliant, can anyone tell us what they are looking for in an exfoliant? We've come a long way since the days of Aapri and now you can have your grains organic, microscopic, glycolic and all have their uses and applications.
We at Ethica favour the micro grains so far as they perform so well, gentle on the sensitive skins but effective as a cell removing paste...also loving pineapple extract to lift cells gently from the surface leaving a radiant glow but, what do the rest of you think?  Tell us and we'll take your advice.....looking forward to hearing from you.